/* ieee-utils/fp-darwin.c
 * 
 * Copyright (C) 2001 Rodney Sparapani <rsparapa@mcw.edu>
 * 
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or (at
 * your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <architecture/ppc/fp_regs.h> 
#include <gsl/gsl_ieee_utils.h>
#include <gsl/gsl_errno.h>

int
gsl_ieee_set_mode (int precision, int rounding, int exception_mask)
{
  ppc_fp_scr_t fp_scr = get_fp_scr() ;

  switch (precision)
    {
    case GSL_IEEE_SINGLE_PRECISION:
      GSL_ERROR ("powerpc only supports default precision rounding", GSL_EUNSUP);
      break ;
    case GSL_IEEE_DOUBLE_PRECISION:
      GSL_ERROR ("powerpc only supports default precision rounding", GSL_EUNSUP);
      break ;
    case GSL_IEEE_EXTENDED_PRECISION:
      GSL_ERROR ("powerpc only supports default precision rounding", GSL_EUNSUP);
      break ;
    }

  switch (rounding)
    {
    case GSL_IEEE_ROUND_TO_NEAREST:
      fp_scr.rn = RN_NEAREST ;
      break ;
    case GSL_IEEE_ROUND_DOWN:
      fp_scr.rn = RN_TOWARD_MINUS ;
      break ;
    case GSL_IEEE_ROUND_UP:
      fp_scr.rn = RN_TOWARD_PLUS ;
      break ;
    case GSL_IEEE_ROUND_TO_ZERO:
      fp_scr.rn = RN_TOWARD_ZERO ;
      break ;
    default:
      fp_scr.rn = RN_NEAREST ;
    }


  /* Turn on all the exceptions apart from 'inexact' */
  /* I'm not sure what 'Turn on' means.              */
  /* I'm assuming that enable = 1 and disable = 0    */
  /* and that disable is what is wanted.             */

  if (exception_mask & GSL_IEEE_MASK_INVALID)
    fp_scr.ve = 0 ;				//ve bit:  invalid op exception enable

  if (exception_mask & GSL_IEEE_MASK_DENORMALIZED)
    GSL_ERROR ("powerpc does not support the denormalized operand exception. "
               "Use 'mask-denormalized' to work around this.", GSL_EUNSUP) ;

  if (exception_mask & GSL_IEEE_MASK_DIVISION_BY_ZERO)
    fp_scr.ze = 0 ;                          	//ze bit:  zero divide exception enable

  if (exception_mask & GSL_IEEE_MASK_OVERFLOW)
    fp_scr.oe = 0 ;                         	//oe bit:  overflow exception enable

  if (exception_mask & GSL_IEEE_MASK_UNDERFLOW)
    fp_scr.ue  = 0 ;                        	//ue bit:  underflow exception enable

  if (exception_mask & GSL_IEEE_TRAP_INEXACT)
    {
      fp_scr.xe = 1 ;                    	//xe bit:  inexact exception enable
    }
  else
    {
      fp_scr.xe = 1 ;                  
    }

  set_fp_scr(fp_scr);

  return GSL_SUCCESS ;

}
